The present invention relates to a fluid bearing for journalling shafts and in particular to a hydrostatic and/or aerostatic radial and axial load carrying bearings.
Fluid bearings are commonly employed to journal high speed rotary shafts such as yarn spinning or twisting spindles. In general such bearings comprise an outer shell or housing which defines with the shaft one or more compression pockets distributed about the periphery of the shaft into which a fluid under pressure is supplied. Shifting of the shaft under either radial or axial loads displace pressurized fluid so that an increasing pressure is created in the compression pocket. In order to stabilize the shaft it is necessary to control the flow of fluid into the pocket and out of the pocket so as to increase and reduce the flow in dependence of the load shifting. It is well known to form fluid bearings in such a way that only one conduit is needed to supply the pressure medium to the bearing. Consequently, only one pump is needed. In such bearings, in order to obtain a given rigidity and supporting capacity, it is customary to incorporate within the housing a fixed or constant throttling means as for instance a diaphragm, a jet nozzle, or a capillary tube. Such fixed throttling means controls the inlet of fluid. This type of bearing, owing to its low constructional outlay and cost, are relatively cheap to manufacture. On the other hand they have the drawback that the load carrying capacity and the bearing rigidity, obtained during operation are not very high.
Bearings, which have only one pump to pressurize the oil or fluid supply, also includes those in which restrictor and discharge valves are arranged outside the bearing. In this manner the resistance to the movement of fluid through the bearing can be adjusted manually. Since the restrictor resistance remains constant during operation even in this type of bearing, this measure does not furnish any appreciable improvement in the rigidity of the bearing. A further drawback lies in the fact that a bearing having a plurality of compression pockets or compartments requires a conduit tube running from each restrictor valve point to each of the pockets. In the case of a spindle bearing in general use, an average of ten such conduits are needed.
It has been also well known to furnish each bearing compression pocket with an individual pump of its own. With this system, higher bearing rigidity and carrying capacity can be obtained. At the same time, however, a great outlay in cost is required for the pump, fluid conduits and other supply installations.
Finally, fluid bearings have become known in which throttling valves responsive to load conditions have been provided. With this system high bearing rigidity and carrying capacity can likewise be obtained. The outlay in cost and the number of parts is still relatively high and is not much of an improvement over those bearings in which a pump is supplied for each bearing compression compartment. Furthermore, in both last mentioned systems there is a greater liability for breakdown of the entire bearing and running behavior is very difficult to predict mathematically.
It is an object of the present invention to provide a fluid bearing system overcoming the defects and disadvantages of the known prior art bearings.
It is a further object of the present invention to provide a fluid bearing system having need for only one pump or one source of fluid under pressure and employing fixed throttling means integrated within the bearing itself.
It is still another object of the present invention to provide a fluid bearing system having a increased load capacity and rigidity.
It is another object of the present invention to provide a fluid bearing system which is suitable for radial and/or axial load conditions.
It is another object of the present invention to provide a fluid bearing system employing a choke or throttling valve means directly responsive to load conditions and which means comprises restrictor entrance and discharge openings into the compression chamber so that the same may be varied in dependence upon actual movement of the shaft.
These objects, other objects, and numerous advantages will be apparent from the following disclosure.